Add Go 1.16 to CI and drop 1.12 specific code (#1850)

* Correct incorrect years in CHANGELOG.md
* CI tests with last 4 versions. Remove 1.12 and below specific code
* Rename proxy test

middleware/proxy_test.go

@@ -2,6 +2,7 @@ package middleware
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"io/ioutil"
 	"net"
@@ -9,7 +10,9 @@ import (
 	"net/http/httptest"
 	"net/url"
 	"regexp"
+	"sync"
 	"testing"
+	"time"
 
 	"github.com/labstack/echo/v4"
 	"github.com/stretchr/testify/assert"
@@ -302,3 +305,73 @@ func TestProxyRewriteRegex(t *testing.T) {
 		})
 	}
 }
+
+func TestProxyError(t *testing.T) {
+	// Setup
+	url1, _ := url.Parse("http://127.0.0.1:27121")
+	url2, _ := url.Parse("http://127.0.0.1:27122")
+
+	targets := []*ProxyTarget{
+		{
+			Name: "target 1",
+			URL:  url1,
+		},
+		{
+			Name: "target 2",
+			URL:  url2,
+		},
+	}
+	rb := NewRandomBalancer(nil)
+	// must add targets:
+	for _, target := range targets {
+		assert.True(t, rb.AddTarget(target))
+	}
+
+	// must ignore duplicates:
+	for _, target := range targets {
+		assert.False(t, rb.AddTarget(target))
+	}
+
+	// Random
+	e := echo.New()
+	e.Use(Proxy(rb))
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	rec := httptest.NewRecorder()
+
+	// Remote unreachable
+	rec = httptest.NewRecorder()
+	req.URL.Path = "/api/users"
+	e.ServeHTTP(rec, req)
+	assert.Equal(t, "/api/users", req.URL.Path)
+	assert.Equal(t, http.StatusBadGateway, rec.Code)
+}
+
+func TestClientCancelConnectionResultsHTTPCode499(t *testing.T) {
+	var timeoutStop sync.WaitGroup
+	timeoutStop.Add(1)
+	HTTPTarget := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		timeoutStop.Wait() // wait until we have canceled the request
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer HTTPTarget.Close()
+	targetURL, _ := url.Parse(HTTPTarget.URL)
+	target := &ProxyTarget{
+		Name: "target",
+		URL:  targetURL,
+	}
+	rb := NewRandomBalancer(nil)
+	assert.True(t, rb.AddTarget(target))
+	e := echo.New()
+	e.Use(Proxy(rb))
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	ctx, cancel := context.WithCancel(req.Context())
+	req = req.WithContext(ctx)
+	go func() {
+		time.Sleep(10 * time.Millisecond)
+		cancel()
+	}()
+	e.ServeHTTP(rec, req)
+	timeoutStop.Done()
+	assert.Equal(t, 499, rec.Code)
+}